Esprit exhaust flow improvements

The largest obstacles to Esprit exhaust performance improvement are:

1. boost restriction limited to 7psi (despite advertised 9.5 psi),
2. OE turbocharger turbine exducer port diameter (1.90") is too small for good flow. Replacement turbo turbine should have ~2" exducer to reduce exhaust gases back-pressure /choking.
3. Turbo-to-down pipe adapter, (also acting as an external w/gate gas mixing chamber), is waaay too restrictive.

As I said before, the adapter/extension on the 1984 - 1988 turbos cannot be opened up, because the wall of inner passage tube is too thin. I.D. of the tube measures 1.9" and the wall thickness is only 2.7 mm. If larger /improved turbocharger installation is intended, the OE adapter has to be redesigned!

OEM 84-88 Turbochargers have a restrictive 48mm turbine port (Yikes!).
New turbine cover with a larger port should be found and a new larger wheel fitted. Reduction in back pressure is amazing.
With this mod, the recirculation BOV installation is highly recommended to prevent turbo surges.

If anyone thinks about modifying this area on your Turbo car (late G-body as well as Stevens USA/Australian Esprits equipped with K-Jetronic injection), please be informed, that I am in the process of quoting of the custom adapter with a larger throat.
 

See pics of the prototype, below.  Inner pipe measures = 57/8 mm dia I.D.
5 bolt flange will be replaced by "stock" 4 bolt style flange, like in the last picture.
Please let me know if you want one like that for your car.

At the moment, I can't give you a definite price, but it will drop when more parts are ordered. 

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As I said before, the adapter/extension and a turbine on the 1984 - 1988 turbo Esprits are the most restrictive elements of the whole system.

The extension cannot be machined larger. The wall of inner passage tube is too thin. The I.D. of the tube measures 1.9" and the wall thickness is only 2.7 mm. An improved turbocharger with larger turbine should be also considered.

In the previous post, I considered making part similar to Mike Rodriques adapter, but I found a simpler and more elegant way to achieve similar or better results.

1. Since OE cast iron exhaust header with equal length matched primaries flows very well, so there is no need to replace it, unless it is badly cracked or owner wants to save some weight.

2. The OE turbo . 63 a/r turbine cover can be machined to accept 2.2"-2.3" exducer wheel. 360 bearing or 3x ball bearing CHRA w/oil&water cooling is required. Also, OE .42 a/r compressor cover needs to be machined to Super 60 trim and new billet wheel installed.

3. New adapter can be easily made with 3" OD, 1/4" wall stainless 316 or 321 alloy pipe, 3/5" square flange and 3" v-clamp. It gives "0" restriction.

4. 

5. OE 90 deg expansion chamber w/pre CAT pipe needs flared flange cut off and 3" V-clamp collar welded on.

6. 

7. Modern Tial 38mm waste gate is connected to the cast OE w/g extension (44mm in) and 38mm dump pipe merges with 90 deg elbow pipe just in front the pre-CAT.

8. 

9. 

10. 1984 - 1988 turbo Esprits down pipes are 3" OD, so there is no need for any upgrades. OE muffler can be replaced by much lighter Magnaflow resonator PN# 12649 or 12869